.TH LDAP_GET_OPTION 3 "RELEASEDATE" "OpenLDAP LDVERSION"
.\" $OpenLDAP$
.\" Copyright 1998-2022 The OpenLDAP Foundation All Rights Reserved.
.\" Copying restrictions apply.  See COPYRIGHT/LICENSE.
.SH NAME
ldap_get_option, ldap_set_option \- LDAP option handling routines
.SH LIBRARY
OpenLDAP LDAP (libldap, \-lldap)
.SH SYNOPSIS
.nf
.B #include <ldap.h>
.LP
.BI "int ldap_get_option(LDAP *" ld ", int " option ", void *" outvalue ");"
.LP
.BI "int ldap_set_option(LDAP *" ld ", int " option ", const void *" invalue ");"
.SH DESCRIPTION
.LP
These routines provide access to options stored either in a LDAP handle
or as global options, where applicable.
They make use of a neutral interface, where the type of the value
either retrieved by 
.BR ldap_get_option (3)
or set by
.BR ldap_set_option (3)
is cast to 
.BR "void *" .
The actual type is determined based on the value of the
.B option
argument.
Global options are set/retrieved by passing a NULL LDAP handle. LDAP handles
inherit their default settings from the global options in effect at the time
the handle is created.
.TP
.B LDAP_OPT_API_FEATURE_INFO
Fills-in a 
.BR "LDAPAPIFeatureInfo" ;
.BR outvalue 
must be a 
.BR "LDAPAPIFeatureInfo *" ,
pointing to an already allocated struct.
The
.B ldapaif_info_version
field of the struct must be initialized to
.B LDAP_FEATURE_INFO_VERSION
before making the call. The
.B ldapaif_name
field must be set to the name of a feature to query.
This is a read-only option.
.TP
.B LDAP_OPT_API_INFO
Fills-in a 
.BR "LDAPAPIInfo" ;
.BR outvalue 
must be a 
.BR "LDAPAPIInfo *" ,
pointing to an already allocated struct. The
.B ldapai_info_version
field of the struct must be initialized to
.B LDAP_API_INFO_VERSION
before making the call.
If the version passed in does not match the current library
version, the expected version number will be stored in the
struct and the call will fail.
The caller is responsible for freeing the elements of the
.B ldapai_extensions
array and the array itself using
.BR ldap_memfree (3).
The caller must also free the
.BR ldapi_vendor_name .
This is a read-only option.
.TP
.B LDAP_OPT_CLIENT_CONTROLS
Sets/gets the client-side controls to be used for all operations.
This is now deprecated as modern LDAP C API provides replacements
for all main operations which accepts client-side controls as
explicit arguments; see for example
.BR ldap_search_ext (3),
.BR ldap_add_ext (3),
.BR ldap_modify_ext (3)
and so on.
.BR outvalue
must be 
.BR "LDAPControl ***" ,
and the caller is responsible of freeing the returned controls, if any,
by calling 
.BR ldap_controls_free (3),
while
.BR invalue
must be 
.BR "LDAPControl *const *" ;
the library duplicates the controls passed via
.BR invalue .
.TP
.B LDAP_OPT_CONNECT_ASYNC
Sets/gets the status of the asynchronous connect flag.
.BR invalue
should either be
.BR LDAP_OPT_OFF
or
.BR LDAP_OPT_ON ;
.BR outvalue
must be
.BR "int *" .
When set, the library will call
.BR connect (2)
and return, without waiting for response.
This leaves the handle in a connecting state.
Subsequent calls to library routines will poll for completion
of the connect before performing further operations.
As a consequence, library calls that need to establish a connection
with a DSA do not block even for the network timeout
(option
.BR LDAP_OPT_NETWORK_TIMEOUT ).
This option is OpenLDAP specific.
.TP
.B LDAP_OPT_CONNECT_CB
This option allows to set a connect callback.
.B invalue
must be a 
.BR "const struct ldap_conncb *" .
Callbacks are executed in last in-first served order.
Handle-specific callbacks are executed first, followed by global ones.
Right before freeing the callback structure, the
.B lc_del
callback handler is passed a 
.B NULL
.BR Sockbuf .
Calling
.BR ldap_get_option (3)
for this option removes the callback whose pointer matches
.BR outvalue .
This option is OpenLDAP specific.
.TP
.B LDAP_OPT_DEBUG_LEVEL
Sets/gets the debug level of the client library.
.BR invalue
must be a 
.BR "const int *" ;
.BR outvalue
must be a
.BR "int *" .
Valid debug levels are 
.BR LDAP_DEBUG_ANY ,
.BR LDAP_DEBUG_ARGS ,
.BR LDAP_DEBUG_BER ,
.BR LDAP_DEBUG_CONNS ,
.BR LDAP_DEBUG_NONE ,
.BR LDAP_DEBUG_PACKETS ,
.BR LDAP_DEBUG_PARSE ,
and
.BR LDAP_DEBUG_TRACE .
This option is OpenLDAP specific.
.TP
.B LDAP_OPT_DEFBASE
Sets/gets a string containing the DN to be used as default base
for search operations.
.BR outvalue
must be a
.BR "char **" ,
and the caller is responsible of freeing the returned string by calling
.BR ldap_memfree (3),
while
.BR invalue
must be a 
.BR "const char *" ;
the library duplicates the corresponding string.
This option is OpenLDAP specific.
.TP
.B LDAP_OPT_DEREF
Sets/gets the value that defines when alias dereferencing must occur.
.BR invalue
must be
.BR "const int *" ;
.BR outvalue 
must be
.BR "int *" .
They cannot be NULL.
The value of 
.BR *invalue
should be one of
.BR LDAP_DEREF_NEVER
(the default),
.BR LDAP_DEREF_SEARCHING ,
.BR LDAP_DEREF_FINDING ,
or
.BR LDAP_DEREF_ALWAYS .
Note that this has ever been the only means to determine alias dereferencing
within search operations.
.TP
.B LDAP_OPT_DESC
Returns the file descriptor associated to the socket buffer
of the LDAP handle passed in as 
.BR ld ;
.BR outvalue
must be a 
.BR "int *" .
This is a read-only, handle-specific option.
.TP
.B LDAP_OPT_DIAGNOSTIC_MESSAGE
Sets/gets a string containing the error string associated to the LDAP handle.
This option was formerly known as 
.BR LDAP_OPT_ERROR_STRING .
.BR outvalue
must be a
.BR "char **" ,
and the caller is responsible of freeing the returned string by calling
.BR ldap_memfree (3),
while
.BR invalue
must be a 
.BR "char *" ;
the library duplicates the corresponding string.
.TP
.B LDAP_OPT_HOST_NAME
Sets/gets a space-separated list of hosts to be contacted by the library 
when trying to establish a connection.
This is now deprecated in favor of
.BR LDAP_OPT_URI .
.BR outvalue
must be a 
.BR "char **" ,
and the caller is responsible of freeing the resulting string by calling
.BR ldap_memfree (3),
while
.BR invalue
must be a 
.BR "const char *" ;
the library duplicates the corresponding string.
.TP
.B LDAP_OPT_MATCHED_DN
Sets/gets a string containing the matched DN associated to the LDAP handle.
.BR outvalue
must be a
.BR "char **" ,
and the caller is responsible of freeing the returned string by calling
.BR ldap_memfree (3),
while
.BR invalue
must be a 
.BR "const char *" ;
the library duplicates the corresponding string.
.TP
.B LDAP_OPT_NETWORK_TIMEOUT
Sets/gets the network timeout value after which
.BR poll (2)/ select (2) 
following a 
.BR connect (2) 
returns in case of no activity.
.B outvalue
must be a 
.BR "struct timeval **"
(the caller has to free
.BR *outvalue
using
.BR ldap_memfree (3)),
and
.B invalue
must be a 
.BR "const struct timeval *" .
They cannot be NULL. Using a struct with seconds set to \-1 results
in an infinite timeout, which is the default.
This option is OpenLDAP specific.
.TP
.B LDAP_OPT_PROTOCOL_VERSION
Sets/gets the protocol version.
.BR outvalue
and
.BR invalue
must be 
.BR "int *" .
.TP
.B LDAP_OPT_REFERRAL_URLS
Sets/gets an array containing the referral URIs associated to the LDAP handle.
.BR outvalue
must be a
.BR "char ***" ,
and the caller is responsible of freeing the returned string by calling
.BR ldap_memvfree (3),
while
.BR invalue
must be a NULL-terminated
.BR "char *const *" ;
the library duplicates the corresponding string.
This option is OpenLDAP specific.
.TP
.B LDAP_OPT_REFERRALS
Determines whether the library should implicitly chase referrals or not.
.BR invalue
must be 
.BR "const int *" ;
its value should either be
.BR LDAP_OPT_OFF
or
.BR LDAP_OPT_ON .
.BR outvalue
must be
.BR "int *" .
.\".TP
.\".B LDAP_OPT_REFHOPLIMIT
.\"This option is OpenLDAP specific.
.\"It is not currently implemented.
.TP
.B LDAP_OPT_RESTART
Determines whether the library should implicitly restart connections (FIXME).
.BR invalue
must be 
.BR "const int *" ;
its value should either be
.BR LDAP_OPT_OFF
or
.BR LDAP_OPT_ON .
.BR outvalue
must be
.BR "int *" .
.TP
.B LDAP_OPT_RESULT_CODE
Sets/gets the LDAP result code associated to the handle.
This option was formerly known as
.BR LDAP_OPT_ERROR_NUMBER .
.BR invalue
must be a 
.BR "const int *" .
.BR outvalue
must be a
.BR "int *" .
.TP
.B LDAP_OPT_SERVER_CONTROLS
Sets/gets the server-side controls to be used for all operations.
This is now deprecated as modern LDAP C API provides replacements
for all main operations which accepts server-side controls as
explicit arguments; see for example
.BR ldap_search_ext (3),
.BR ldap_add_ext (3),
.BR ldap_modify_ext (3)
and so on.
.BR outvalue
must be 
.BR "LDAPControl ***" ,
and the caller is responsible of freeing the returned controls, if any,
by calling 
.BR ldap_controls_free (3),
while
.BR invalue
must be 
.BR "LDAPControl *const *" ;
the library duplicates the controls passed via
.BR invalue .
.TP
.B LDAP_OPT_SESSION_REFCNT
Returns the reference count associated with the LDAP handle passed in as
.BR ld ;
.BR outvalue
must be a
.BR "int *" .
This is a read-only, handle-specific option.
This option is OpenLDAP specific.
.TP
.B LDAP_OPT_SIZELIMIT
Sets/gets the value that defines the maximum number of entries
to be returned by a search operation.
.BR invalue
must be
.BR "const int *" ,
while
.BR outvalue
must be
.BR "int *" ;
They cannot be NULL.
.TP
.B LDAP_OPT_SOCKBUF
Returns a pointer to the socket buffer of the LDAP handle passed in as
.BR ld ;
.BR outvalue
must be a 
.BR "Sockbuf **" .
This is a read-only, handle-specific option.
This option is OpenLDAP specific.
.TP
.B LDAP_OPT_SOCKET_BIND_ADDRESSES
Sets/gets a space-separated list of IP Addresses used as binding interface
to remote server when trying to establish a connection. Only one valid IPv4
address and/or one valid IPv6 address are allowed in the list.
.BR outvalue
must be a
.BR "char **",
and the caller is responsible of freeing the returned string by calling
.BR ldap_memfree (3),
while
.BR invalue
must be a
.BR "const char *" ;
the library duplicates the corresponding string.
.TP
.B LDAP_OPT_TIMELIMIT
Sets/gets the value that defines the time limit after which
a search operation should be terminated by the server.
.BR invalue
must be
.BR "const int *" ,
while
.BR outvalue
must be
.BR "int *" ,
and they cannot be NULL.
.TP
.B LDAP_OPT_TIMEOUT
Sets/gets a timeout value for the synchronous API calls.
.B outvalue
must be a 
.BR "struct timeval **"
(the caller has to free
.BR *outvalue
using
.BR ldap_memfree (3)),
and
.B invalue
must be a 
.BR "struct timeval *" ,
and they cannot be NULL. Using a struct with seconds set to \-1 results
in an infinite timeout, which is the default.
This option is OpenLDAP specific.
.TP
.B LDAP_OPT_URI
Sets/gets a comma- or space-separated list of URIs to be contacted by the library 
when trying to establish a connection.
.BR outvalue
must be a 
.BR "char **" ,
and the caller is responsible of freeing the resulting string by calling
.BR ldap_memfree (3),
while
.BR invalue
must be a 
.BR "const char *" ;
the library parses the string into a list of 
.BR LDAPURLDesc
structures, so the invocation of 
.BR ldap_set_option (3)
may fail if URL parsing fails.
URIs may only contain the
.BR schema ,
the
.BR host ,
and the
.BR port
fields.
This option is OpenLDAP specific.
.TP
.B LDAP_OPT_KEEPCONN
Instructs
.BR ldap_result (3)
to keep the connection open on read error or if Notice of Disconnection is received. In these cases, the connection should be closed by the caller.
This option is OpenLDAP specific.
.TP
.B LDAP_OPT_TCP_USER_TIMEOUT
Allows to configure TCP_USER_TIMEOUT in milliseconds on the connection, overriding the operating system setting.
This option is OpenLDAP specific and supported only on Linux 2.6.37 or higher.

.SH SASL OPTIONS
The SASL options are OpenLDAP specific.
.TP
.B LDAP_OPT_X_SASL_AUTHCID
Gets the SASL authentication identity;
.BR outvalue
must be a
.BR "char **" ,
its content needs to be freed by the caller using
.BR ldap_memfree (3).
.TP
.B LDAP_OPT_X_SASL_AUTHZID
Gets the SASL authorization identity;
.BR outvalue
must be a
.BR "char **" ,
its content needs to be freed by the caller using
.BR ldap_memfree (3).
.TP
.B LDAP_OPT_X_SASL_MAXBUFSIZE
Gets/sets SASL maximum buffer size;
.BR invalue
must be
.BR "const ber_len_t *" ,
while
.BR outvalue
must be
.BR "ber_len_t *" .
See also
.BR LDAP_OPT_X_SASL_SECPROPS .
.TP
.B LDAP_OPT_X_SASL_MECH
Gets the SASL mechanism;
.BR outvalue
must be a
.BR "char **" ,
its content needs to be freed by the caller using
.BR ldap_memfree (3).
.TP
.B LDAP_OPT_X_SASL_MECHLIST
Gets the list of the available mechanisms,
in form of a NULL-terminated array of strings;
.BR outvalue
must be
.BR "char ***" .
The caller must not free or otherwise muck with it.
.TP
.B LDAP_OPT_X_SASL_NOCANON
Sets/gets the NOCANON flag.
When unset, the hostname is canonicalized.
.BR invalue
must be
.BR "const int *" ;
its value should either be
.BR LDAP_OPT_OFF
or
.BR LDAP_OPT_ON .
.BR outvalue
must be
.BR "int *" .
.TP
.B LDAP_OPT_X_SASL_REALM
Gets the SASL realm;
.BR outvalue
must be a
.BR "char **" ,
its content needs to be freed by the caller using
.BR ldap_memfree (3).
.TP
.B LDAP_OPT_X_SASL_SECPROPS
Sets the SASL secprops;
.BR invalue
must be a
.BR "char *" ,
containing a comma-separated list of properties.
Legal values are:
.BR none ,
.BR nodict ,
.BR noplain ,
.BR noactive ,
.BR passcred ,
.BR forwardsec ,
.BR noanonymous ,
.BR minssf=<minssf> ,
.BR maxssf=<maxssf> ,
.BR maxbufsize=<maxbufsize> .
.TP
.B LDAP_OPT_X_SASL_SSF
Gets the SASL SSF;
.BR outvalue
must be a
.BR "ber_len_t *" .
.TP
.B LDAP_OPT_X_SASL_SSF_EXTERNAL
Sets the SASL SSF value related to an authentication
performed using an EXTERNAL mechanism;
.BR invalue
must be a
.BR "const ber_len_t *" .
.TP
.B LDAP_OPT_X_SASL_SSF_MAX
Gets/sets SASL maximum SSF;
.BR invalue
must be
.BR "const ber_len_t *" ,
while
.BR outvalue
must be
.BR "ber_len_t *" .
See also
.BR LDAP_OPT_X_SASL_SECPROPS .
.TP
.B LDAP_OPT_X_SASL_SSF_MIN
Gets/sets SASL minimum SSF;
.BR invalue
must be
.BR "const ber_len_t *" ,
while
.BR outvalue
must be
.BR "ber_len_t *" .
See also
.BR LDAP_OPT_X_SASL_SECPROPS .
.TP
.B LDAP_OPT_X_SASL_USERNAME
Gets the SASL username;
.BR outvalue
must be a
.BR "char **" .
Its content needs to be freed by the caller using
.BR ldap_memfree (3).
.B LDAP_OPT_X_SASL_CBINDING
Sets/gets the channel-binding type to use in SASL,
one of
.BR LDAP_OPT_X_SASL_CBINDING_NONE
(the default),
.BR LDAP_OPT_X_SASL_CBINDING_TLS_UNIQUE
the "tls-unique" type from RFC 5929.
.BR LDAP_OPT_X_SASL_CBINDING_TLS_ENDPOINT
the "tls-server-end-point" from RFC 5929, compatible with Windows.
.BR invalue
must be
.BR "const int *" ;
.BR outvalue
must be
.BR "int *" .
.TP
.SH TCP OPTIONS
The TCP options are OpenLDAP specific.
Mainly intended for use with Linux, they may not be portable.
.TP
.B LDAP_OPT_X_KEEPALIVE_IDLE
Sets/gets the number of seconds a connection needs to remain idle
before TCP starts sending keepalive probes.
.BR invalue
must be
.BR "const int *" ;
.BR outvalue
must be
.BR "int *" .
.TP
.B LDAP_OPT_X_KEEPALIVE_PROBES
Sets/gets the maximum number of keepalive probes TCP should send
before dropping the connection.
.BR invalue
must be
.BR "const int *" ;
.BR outvalue
must be
.BR "int *" .
.TP
.B LDAP_OPT_X_KEEPALIVE_INTERVAL
Sets/gets the interval in seconds between individual keepalive probes.
.BR invalue
must be
.BR "const int *" ;
.BR outvalue
must be
.BR "int *" .
.SH TLS OPTIONS
The TLS options are OpenLDAP specific.
.\".TP
.\".B LDAP_OPT_X_TLS
.\"Sets/gets the TLS mode.
.TP
.B LDAP_OPT_X_TLS_CACERTDIR
Sets/gets the path of the directories containing CA certificates.
Multiple directories may be specified, separated by a semi-colon.
.BR invalue
must be
.BR "const char *" ;
.BR outvalue
must be
.BR "char **" ,
and its contents need to be freed by the caller using
.BR ldap_memfree (3).
.TP
.B LDAP_OPT_X_TLS_CACERTFILE
Sets/gets the full-path of the CA certificate file.
.BR invalue
must be
.BR "const char *" ;
.BR outvalue
must be
.BR "char **" ,
and its contents need to be freed by the caller using
.BR ldap_memfree (3).
.TP
.B LDAP_OPT_X_TLS_CERTFILE
Sets/gets the full-path of the certificate file.
.BR invalue
must be
.BR "const char *" ;
.BR outvalue
must be
.BR "char **" ,
and its contents need to be freed by the caller using
.BR ldap_memfree (3).
.TP
.B LDAP_OPT_X_TLS_CIPHER
Gets the cipher being used on an established TLS session.
.BR outvalue
must be
.BR "char **" ,
and its contents need to be freed by the caller using
.BR ldap_memfree (3).
.TP
.B LDAP_OPT_X_TLS_CIPHER_SUITE
Sets/gets the allowed cipher suite.
.BR invalue
must be
.BR "const char *" ;
.BR outvalue
must be
.BR "char **" ,
and its contents need to be freed by the caller using
.BR ldap_memfree (3).
.TP
.B LDAP_OPT_X_TLS_CONNECT_ARG
Sets/gets the connection callback argument.
.BR invalue
must be
.BR "const void *" ;
.BR outvalue
must be
.BR "void **" .
.TP
.B LDAP_OPT_X_TLS_CONNECT_CB
Sets/gets the connection callback handle.
.BR invalue
must be
.BR "const LDAP_TLS_CONNECT_CB *" ;
.BR outvalue
must be
.BR "LDAP_TLS_CONNECT_CB **" .
.TP
.B LDAP_OPT_X_TLS_CRLCHECK
Sets/gets the CRL evaluation strategy, one of
.BR LDAP_OPT_X_TLS_CRL_NONE ,
.BR LDAP_OPT_X_TLS_CRL_PEER ,
or
.BR LDAP_OPT_X_TLS_CRL_ALL .
.BR invalue
must be
.BR "const int *" ;
.BR outvalue
must be
.BR "int *" .
Requires OpenSSL.
.TP
.B LDAP_OPT_X_TLS_CRLFILE
Sets/gets the full-path of the CRL file.
.BR invalue
must be
.BR "const char *" ;
.BR outvalue
must be
.BR "char **" ,
and its contents need to be freed by the caller using
.BR ldap_memfree (3).
This option is only valid for GnuTLS.
.TP
.B LDAP_OPT_X_TLS_CTX
Sets/gets the TLS library context. New TLS sessions will inherit their
default settings from this library context.
.BR invalue
must be
.BR "const void *" ;
.BR outvalue
must be
.BR "void **" .
When using the OpenSSL library this is an SSL_CTX*. When using other
crypto libraries this is a pointer to an OpenLDAP private structure.
Applications generally should not use this option or attempt to
manipulate this structure.
.TP
.B LDAP_OPT_X_TLS_DHFILE
Gets/sets the full-path of the file containing the parameters
for Diffie-Hellman ephemeral key exchange.
.BR invalue
must be
.BR "const char *" ;
.BR outvalue
must be
.BR "char **" ,
and its contents need to be freed by the caller using
.BR ldap_memfree (3).
.TP
.B LDAP_OPT_X_TLS_ECNAME
Gets/sets the name of the curve(s) used for
elliptic curve key exchanges.
.BR invalue
must be
.BR "const char *" ;
.BR outvalue
must be
.BR "char **" ,
and its contents need to be freed by the caller using
.BR ldap_memfree (3).
Ignored by GnuTLS. In GnuTLS a curve may be selected
in the cipher suite specification.
.TP
.B LDAP_OPT_X_TLS_KEYFILE
Sets/gets the full-path of the certificate key file.
.BR invalue
must be
.BR "const char *" ;
.BR outvalue
must be
.BR "char **" ,
and its contents need to be freed by the caller using
.BR ldap_memfree (3).
.TP
.B LDAP_OPT_X_TLS_NEWCTX
Instructs the library to create a new TLS library context.
.BR invalue
must be
.BR "const int *" .
A non-zero value pointed to by
.BR invalue
tells the library to create a context for a server.
.TP
.B LDAP_OPT_X_TLS_PEERCERT
Gets the peer's certificate in DER format from an established TLS session.
.BR outvalue
must be
.BR "struct berval *" ,
and the data it returns needs to be freed by the caller using
.BR ldap_memfree (3).
.TP
.B LDAP_OPT_X_TLS_PROTOCOL_MAX
Sets/gets the maximum protocol version.
.BR invalue
must be
.BR "const int *" ;
.BR outvalue
must be
.BR "int *" .
.TP
.B LDAP_OPT_X_TLS_PROTOCOL_MIN
Sets/gets the minimum protocol version.
.BR invalue
must be
.BR "const int *" ;
.BR outvalue
must be
.BR "int *" .
.TP
.B LDAP_OPT_X_TLS_RANDOM_FILE
Sets/gets the random file when
.B /dev/random
and
.B /dev/urandom
are not available.
.BR invalue
must be
.BR "const char *" ;
.BR outvalue
must be
.BR "char **" ,
and its contents need to be freed by the caller using
.BR ldap_memfree (3).
Ignored by GnuTLS older than version 2.2.
.TP
.B LDAP_OPT_X_TLS_REQUIRE_CERT
Sets/gets the peer certificate checking strategy,
one of
.BR LDAP_OPT_X_TLS_NEVER ,
.BR LDAP_OPT_X_TLS_HARD ,
.BR LDAP_OPT_X_TLS_DEMAND ,
.BR LDAP_OPT_X_TLS_ALLOW ,
.BR LDAP_OPT_X_TLS_TRY .
.TP
.B LDAP_OPT_X_TLS_REQUIRE_SAN
Sets/gets the peer certificate subjectAlternativeName checking strategy,
one of
.BR LDAP_OPT_X_TLS_NEVER ,
.BR LDAP_OPT_X_TLS_HARD ,
.BR LDAP_OPT_X_TLS_DEMAND ,
.BR LDAP_OPT_X_TLS_ALLOW ,
.BR LDAP_OPT_X_TLS_TRY .
.TP
.B LDAP_OPT_X_TLS_SSL_CTX
Gets the TLS session context associated with this handle.
.BR outvalue
must be
.BR "void **" .
When using the OpenSSL library this is an SSL*. When using other
crypto libraries this is a pointer to an OpenLDAP private structure.
Applications generally should not use this option.
.TP
.B LDAP_OPT_X_TLS_VERSION
Gets the TLS version being used on an established TLS session.
.BR outvalue
must be
.BR "char **" ,
and its contents need to be freed by the caller using
.BR ldap_memfree (3).
.SH ERRORS
On success, the functions return
.BR LDAP_OPT_SUCCESS ,
while they may return
.B LDAP_OPT_ERROR
to indicate a generic option handling error.
Occasionally, more specific errors can be returned, like
.B LDAP_NO_MEMORY
to indicate a failure in memory allocation.
.SH NOTES
The LDAP libraries with the
.B LDAP_OPT_REFERRALS 
option set to
.B LDAP_OPT_ON
(default value) automatically follow referrals using an anonymous bind.
Application developers are encouraged to either implement consistent
referral chasing features, or explicitly disable referral chasing
by setting that option to
.BR LDAP_OPT_OFF .
.P
The protocol version used by the library defaults to LDAPv2 (now historic),
which corresponds to the
.B LDAP_VERSION2
macro.
Application developers are encouraged to explicitly set
.B LDAP_OPT_PROTOCOL_VERSION
to LDAPv3, using the 
.B LDAP_VERSION3
macro, or to allow users to select the protocol version.
.SH SEE ALSO
.BR ldap (3),
.BR ldap_error (3),
.B RFC 4422
(http://www.rfc-editor.org),
.SH ACKNOWLEDGEMENTS
.so ../Project
